A very thin, small outline, thermally enhanced semiconductor package includes a leadframe that is coined to form locking features on an exposed die pad and on a plurality of extremely narrow, closely spaced leads. The coined features improve the mechanical locking between the leadframe and the plastic body of the package to increase their resistance to delamination and subsequent penetration by moisture, and enable reliable wire bonds to be made to the otherwise extremely narrow leads.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A semiconductor package, comprising: a metal lead frame, including a plurality of elongate leads arrayed around a central region thereof, each lead having a generally planar upper surface, an outer end portion extending away from the central region and defining an outer end, an inner end portion extending toward the central region, and a middle portion extending between the outer and inner end portions, the middle portion being of a lead width and having a lower surface which defines a land; a spatulate bonding pad formed in the inner end portion of each lead and having a bonding pad width which exceeds the lead width, the bonding pad being partially defined by the upper surface of the lead and including a lower bonding pad surface positioned between the upper surface of the lead and the lower surface of the lead which defines the land; and a die pad attached to the lead frame in the central region thereof and adjacent to the inner end portions of the leads, the die pad having an upper surface and a lower surface; and a body of an insulative plastic molded over the die, the die pad, and the leads such that the plastic body surrounds the bonding pads and interlocks with them, and such that the lands are exposed in and substantially flush with a lower surface of the body and the outer ends of the leads are exposed in and substantially flush with a side surface of the body.
2. The semiconductor package of claim 1 , wherein the die pad is attached to the frame by at least one tie-bar.
3. The semiconductor package of claim 1 , wherein the die pad is attached to at least one of the leads by at least one tie-bar.
4. The semiconductor package of claim 3 , wherein each of the bonding pads has a generally circular configuration.
5. The semiconductor package of claim 1 , wherein the lands are rectangular.
6. The semiconductor package of claim 1 , further comprising: a semiconductor die attached to the upper surface of the die pad; and a plurality of conductive wires bonded at opposite ends to pads on a top surface of the die and selected ones of the bonding pads on the leads.
7. The semiconductor package of claim 1 , wherein the lower surface of the die pad has a central portion and a recessed shoulder extending around the central portion, and the plastic body surrounds the recessed shoulder such that the central portion of the lower surface of the die pad is exposed in the lower surface of the body.
8. The semiconductor package of claim 1 , wherein the leadframe comprises an alloy of copper, aluminum, or iron and nickel.
9. The semiconductor package of claim 1 , wherein the insulative plastic of the body comprises an epoxy resin.
10. A lead frame for a semiconductor package, comprising: a plurality of elongate metal leads arrayed around a central region, each lead having a generally planar upper surface, an outer end portion extending away from the central region, an inner end portion extending toward the central region, and a middle portion extending between the outer and inner end portions, the middle portion being of a lead width and having a lower surface which defines a land; a spatulate bonding pad formed into the inner end portion of each of the leads, the spatulate bonding pad of each of the leads having a pad width which exceeds the lead width, the bonding pad being partially defined by the upper surface of the lead and including a lower bonding pad surface positioned between the upper surface of the lead and the lower surface of the lead which defines the land; and a disposable frame connected to the leads.
11. The lead frame of claim 10 , further comprising a die pad disposed in the central region and adjacent the inner end portions of the leads, the die pad having a recessed shoulder extending around a periphery of a lower surface thereof.
12. The semiconductor package of claim 10 , wherein the lands are rectangular.
13. A semiconductor package of a type that includes a metal lead frame having a plurality of elongate leads radiating out from a central die pad, each lead having a generally planar upper surface and a lower surface which defines a land, a semiconductor die mounted on the die pad, a plurality of wire bonds connecting the die to the leads, and a protective plastic body molded over the leads, the die pad, the die, and the wire bonds, the improvement in combination therewith comprising: a spatulate bonding pad formed into an inner end portion of each lead and adjacent to the die pad, the bonding pad having a bonding pad width, the bonding pad being partially defined by the upper surface of the lead and including a lower bonding pad surface positioned between the upper surface of the lead and the lower surface of the lead which defines the land; and the bonding pad width exceeding a lead width of a middle portion of each lead extending between the inner and outer end portions thereof, with the leads, the die pad and the bonding pads having coplanar upper surfaces.
14. The semiconductor package of claim 13 , wherein the wire bonds are connected to the bonding pads.
15. The semiconductor package of claim 13 , wherein the middle portion of each lead has a lower surface defining a land which is exposed through a lower surface of the plastic body.
16. The semiconductor package of claim 15 , wherein the lands are rectangular.
17. The semiconductor package of claim 13 , further comprising a recessed shoulder formed into a periphery of a lower surface of the die pad such that a central portion of the lower surface inside of the shoulder is exposed through a lower surface of the plastic body.
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December 16, 2003
November 15, 2005
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